1. Field of the Invention
The present invention relates to a capsule medical system and a biological information acquiring method for performing human body communications with a capsule medical device inserted into the inside of a subject, such as a patient, to thereby acquire information in the body of the subject.
2. Description of the Related Art
In the field of endoscopes, a swallowable capsule endoscope (one example of a capsule medical device) has appeared in recent years. This capsule endoscope is provided with an imaging function and a radio communication function. After the capsule endoscope is swallowed from a mouth of a subject (hereinafter, it may also be called a human body) such as a patient or the like, for observations (examinations) until it is naturally excreted to the outside of the body, the capsule endoscope sequentially captures information in the body of the subject, for example, images inside internal organs (hereinafter, they may also be called in-vivo images) while moving inside the internal organs, such as a stomach, a small intestine, and the like, by peristaltic movements.
However, since this capsule endoscope is communicating with the outside of the human body by the radio communication function, the power dissipation is increased, the operating time is decreased, and a volume occupied by a primary battery is also increased, so that there has been a problem that reduction in size and improvement in performance of the capsule endoscope are inhibited. Consequently, a human body communication system in which communications between the capsule endoscope inside the human body and a receiving apparatus outside the human body (i.e., human body communications) are performed using the human body as a communication medium has appeared in recent years (refer to Patent Application Publication No. 2006-513001).
In such a human body communication system, currents are generated according to a potential difference between transmitting electrodes formed on a surface of the capsule endoscope, and when the currents flow through the human body, a voltage is induced between two receiving electrodes provided on a surface of the human body, and the receiving apparatus outside the human body receives image signals from the capsule endoscope by this induced voltage. The capsule endoscope that performs the human body communications can transmit image data at a low frequency signal of about 10 MHz without requiring an RF signal of several hundreds of MHz, so that the power dissipation can be reduced extremely.
Moreover, if a position detecting technology for detecting a position of the capsule endoscope inside the human body based on the voltage induced between the receiving electrodes, and the human body communication system are combined by the human body communications, it is possible to achieve a capsule medical system that can acquire in-vivo images of the subject from the capsule endoscope by the human body communications and also detect a position of the capsule endoscope inside the human body upon capturing the in-vivo images.